Mechanical bi-stable device



Nov. 10, 1953 E. A. BROWN MECHANICAL BI-STABLE DEVICE 5 Sheets-Sheet 1 Filed May 23, 1951 INVENTOR. 7 Qlamfirowm Nov. 10, 1953 E. A. BROWN MECHANICAL BI-STABLE DEVICE 5 Sheets-Sheet 2 Filed May 23, 1951 BN U HQ INVENTOR. arQZanfirozwz 3 Sheets-Sheet 3 E; A. BROWN MECHANICAL BI-STABLE DEVICE Nov. 10, 1953 Filed May 23, 1951 INVENTOR. ig garalpm/firqwm BY 7 l I Patented Nov. 10, 1953 UNITED STATES PATENT OFFICE MECHANICAL BI-STABLE DEVICE Application May 23, 1951, Serial .No.:22 7,924:-

8 Claims. (01. ZOO-87) This invention relates to a new mechanical bistable device, that is, to a new mechanical device which hastwo stable conditions to which it. will be operated alternately by application of. successive force pulses to it.

An object of the present invention is to provide a novel and very simple mechanical bi-stable device.

A further object is to' provide a mechanical bistable device having a. minimum number and mass of'moving parts and having great rapidity and reliability of operation and high durability.

A further object is to provide a novel binary counter employing the new mechanical bi-stable device and characterized by great simplicity, reliable accuracy, rapid operation and ruggedness.

Prior mechanical bi-stable devices are relatively complex and, because of the number and mass of the moving parts thereof, do not have desirable rapidity of. operation, and are subject towear which renders them unreliable and in accurate in operation.

The mechanical bi-stable device of the present invention is of extremely simple and durable structure and operates with great rapidity and reliability. It has many" uses including but not limited to known uses of prior mechanical bistable devices, but because of its extreme simplicity, durabality and rapid and reliable operation, it is especially suited for uses in which those qualities are of great importance as, for example, in counting apparatus. The present invention further provides a new, electro-mechanical, binary counter of great simplicity, reliable accuracy, rapid operation and ruggedness.

The foregoing and other objects and advantages of the invention will become apparent from the following description in conjunction with the accompanying drawings in which:

Figs. 1 and 2 are, respectively, a vertical section and a front elevation and partial section, of a mechanical bi-stable device in accordance with the present invention, the section of Fig. 1 being taken on the line l--! of Fig. 2, and the device being shown in one of its two stable conditions;

Figs. 3 and 4 are front elevations similar to Fig. 2' but show the device at difiercnt times during an operation thereof;

Fig. 5 is a front elevation similar to Fig. 2 but shows the device in the other of its two stable positions after completion of the operation depicted in Figs. 3 and 4;

Figs. 6, '7, "8' and 9 are front elevations of modified forms of bi-stable device in ac ordance withv theinvention; and

Fig. 10 is a circuit diagram of a binary counter in.v accordance with the present invention and utilizing electromagnetically operated mechanical bi-stable devices in accordance with the invention.

In. accordance with the present invention, an.

initially straight, flat, elastically flexible spring member 2B. (Figs. 1 to 5-) is supported at its 013-- posite ends by two supports 2| and 22. The member Zli may advantageously be a straight flat length of spring steel ribbon, such as a. length of watch-spring steel, the brand currently identified by the registered trade-mark Elgiloy being eminently suitable. One end 23 of the spring member 20 is pivotally supported inits, respective one, 21,. of the supports, as by engagement of that end of the spring member in a V-shaped groove 2 in that support 21. The other end 25 of the, spring member 23 is rigidly secured. in. the. other support 22 in such manner that. if the spring were permitted to assume a position in which it. would be free of stresses, it would lie fiat in the plane of Fig. l, i. e., in a. plane containing the axis of pivotal support of the opposite end 23 of the spring member 23, and indicated by the line 2c in Fig. 2. One of the supports 2| or 22, preferably the support 2 2 which is rigidly secured to the spring 20, is mounted for limited movement toward and from the pivotally supported end 24, of the spring member.

Preferably, the support 2| is formed as a frame or housing having an opening 21 accommodating the spring member 20, one end of which opening forms the groove 24. The movable support member 22 will then be mounted in a. bore 28' extending through the housing at the opposite end of the opening 21 and aligned with the vertex of the groove 24. Thev movement of the member 22 is limited as by means of a screw stud 29 (Fig. 1) threaded through the side of the frame 2| and extending into a longitudinal groove 36 formed in the member 22. Alternately, the longitudinal movement of the mem ber' 22" may be limited by engagement of the frame 2| alternately with the enlarged inner end of the member 22 and with a collar 25' (Fig. 8) on the reduced stem of the member 22. The. outward limit of movement of the member 22 is such that the ends of the spring member 2|) are maintained closer together than the length of the spring member 20, whereby the, spring member 2 6 is forced into a flexed form such as shown in solid line in Fig. 2. It will be readily apparent that the spring member 29 may alternatively and equally well be bowed out on the opposite side of the plane 26 as shown in Fig. 5. In either case the spring member 26, from its pivoted end 24 to its juncture 3| with the member 22, if not laterally confined, will assume a curved form which, for present purposes, may be assumed to approximate a portion of a sine curve having, for the solid line curve 20 of Fig. 1, the axes a and sin a and extending from at the vertex of the groove 24 to a point somewhat short of 270. A point 32 of zero curvature will be found on the spring member 20 at its intersection with the a axis, corresponding to the 180 point on the curve. A line 33 drawn in the plane of Fig. 2 and parallel to the plane of Fig. 1 (line 26 of Fig. 2) will be tangent to the curve of the spring member 2!] at a point 34 which is in alignment with the point 32 and the juncture 3| of the spring member with the member 22. The portion of the curve of the spring member 20 from the point 3i to the point 34 will be symmetrical about the point 32.

Movement of the member 22 inwardly (down wardly in Figs. 1-5), if the spring member 26 were not laterally outwardly confined, would cause the spring member to bow outwardly farther, i. e., away from the plane 26. However, in accordance with the present invention, a portion of the spring member 23 from its pivoted end 23 to a point 35 somewhat beyond the point 34 is confined against such further movement outwardly, i. e., away from the plane 26. Such confinement is preferably provided by the sur-- face of the frame 2| surrounding the opening 21. Such confinement need not be continuous along the entire length of the spring from the end 24 to the point 35 but may be provided, as by means of a series of abutments (not shown) at a series of points spaced along the outer face of the spring member 23 at points which are sufliciently close together in relation to the stiffness of the spring member to prevent the latter from bowing further outwardly between such points of confinement.

If such confinement extended from the pivoted end 23 only to the point 34, then the unconfined portion from 34 to 3! would be symmetrical about the point 32 so that, upon inward move ment of the member 22, there would be equal probabilities of the portion of the spring member between the points 34 and 3| being forced either toward or from the plane 26. However, the confinement against further movement away from the plane 25 extends to the point 35 which is sufiiciently away from the point 34 in the direction of point 32 to insure that the inward movement of the member 22 will cause the portion 3! to 35 to swing inwardly toward the plane Such further flexing of the spring member 20 by inward movement of the member 22 will cause the spring to peel away from the confining wall of the opening 21 and cause the curved shape of the spring to change progressively through a series of forms, three of which are shown in Fig. 3, one by the solid line 20 and two others by the dotted lines 36 and 31. As the inward movement of the member 22, the concomitant change of curvature of the spring member 20, and the peeling away from the confining wall of the opening 21 progress, the point of zero curvature previously located at point 32 shifts progressively along the spring member 2!} toward the pivoted end 23 as indicated at points 38, 39 and 40 on curves 20, 36 and 31 of Fig. 3. Another point of ZBIO curvature enters the other end of the spring member 23 and also progressively shifts toward the pivoted end 23. This latter point of zero curvature i indicated at 4|, 42 and 43 in Fig. 3. If a straight line is run through the above-mom tioned two points of zero curvature on each of the curve forms successively assumed by the spring member 20, it will be found that such line swings progressively toward the pivoted end 23 of the spring as indicated by the lines 44, 45 and 46 in Fig. 3. When that line, as indicate-cl by the line 46, reache the pivoted end 23 of the spring member 20, the curve form will be approximately that of a portion of the curve of sin b from 0 at the pivoted end 23 of the spring member to somewhat less than 450 at point 3i. the b axis of such curve coinciding with the line 46 and the point of peeling of the spring member 20 from the previously confining wall of the opening 21 will also have progressed to the vertex of the notch 24. Theoretically, the spring member 20 will at that instant reach a condi tion of instability such that it will snap over to the form and position shown in solid line in Fig. 4.

The foregoing portion of the explanation of the action of the spring member, for the sake of simplicity, assumes a perfect spring member and assumes that the confining walls from the notch 24 to the points 35 and 35 exactly coin cide with forms and positions which the outward faces of the spring member would assume in stable rest positions of the device, such as shown in Figs. 4 and 5, even if the spring member were free from lateral confinement. Even when the confining Walls are formed as nearly as is practically possible to the above assumed configuration, the spring member 22 will reach the unstable equilibrium condition, from which it will start to snap toward the solid line position of Fig. 4, somewhat before the spring member has peeled completely away from the confining wall of the frame 2|, that is, somewhat before the line through the two inflection points, or points of zero curvature, intermediate the ends of the pring member reaches the end 23 of the spring member in the vertex of the notch 24.

Preferably, the member 22 is prevented from moving inwardly more than a short distance farther than required to cause the spring member to pass through the condition of instability just described. The groove 30 is preferably just lon enough to secure that result.

When the pressure which moves the member 22 inwardly is withdrawn from it, the member 22 is returned outwardly (upwardly in Figs. 1-5) by the spring member 20. During such outward movement of the member 22, the spring mem* ber 20 progressively changes its curvature through a succession of forms, one intermediate form being shown in dotted line at 4'! in Fig. 4. When the member 22 reaches the outward limit of its return movement, the spring member 23 is in the form and position shown in Fig. 5.

It will be apparent that another reciprocation of the member 22 will cause the spring member 23 to move from the form and position of Fig. 5 back to the form and position of Fig. 2. In such second operation of the device, the changes of form and positions of the spring member 23 will have the same appearance as those which occurred in the first above-described operation would have had if viewed from behind the plane of Figs. 2 to 5.

Thus, successive reciprocation of the memher 22 will cause thespring member 230 to be onerated alternately from each otitstwo stable positions of Figs. 2 and 5 to the other of such positions.

The foregoing explanation, for the sake of simplicity, omits consideration of eifects of inertia and momentum and some other factors which will or may cause the action of the spring member to vary somewhat from complete correspondence with that described above without injuring the eiiectiveness of the device as a bi-stable means. It will be apparent that with the device as shown in Fig. 4, further inward movement'of the member 22, if permitted, would cause the portion of the spring member'ZO between its pivoted end and the point 35' to increase itsv curvature so that, adjacent the pivoted end 23, a portion of the spring member may again be laid on the previously engaged confining wall of the opening 21. If such movement of the member 22 is sufficiently rapid, the last-mentioned portion of the spring member will not have the opportunity to peel fully fromthe wall of the opening 2'! during inward. movement of the member 22 but will remain in contact with the confining wall above the vertex of the notch 24 until the outward return movement of the member 22 hasstarted.

Variations in exact form and dimensions may cause the action of the spring member to vary more or less from complete identity with that described above without seriously interfering with the effectiveness and reliability of the device as a bi-stable means and in fact, such variations may be intentionally secured for useful purposes. For example the configuration of the laterally confining walls from notch 24. to the points and 35' and the locations of these points may be chosen so that, starting from the condition of Fig. l, inward movement of the member. 22 will cause the spring to snap over against the point 35' without fully peeling away from the lower portion of the wall 24, 35. Such a variation may be used to secure a desired timing of the operation of an output member by the portion of the spring member near its end: 23 as will become clear after consideration of Fig. 9.

That portion of the opening 21 in which. the portion 31- 5 (Fig. 2) of the spring member 20 operates may be of any desired contour so long as it does not seriously impede operation of the spring member in generally the above-described manner. In Figs. 2-5, the portion of the opening 2! above the points 35 and 35' is shown as being of a size and form such that, in every position of the spring member, clearance is provided between the spring member and the frame 21 at all points above the points 35 and 35. However, a considerable amount of interference of the frame above the points 35 and 35' with the free movement of the upper portion of the spring member may exist without preventing effective operation of the device generally in the manner described above, even though the curve forms of the spring member may be somewhat altered.

It will be apparent that the ratio of longi tuziinal dimensions to transverse dimensions may be varied greatly in either direction from the proportions shown in Fig. I. In other words, the amplitude of throw of the spring member .2!) relative to the length of the spring member can be varied from a very small value to a value considerably greater than shown in Fig. 1,. provided, of course, that. aspring member of sufficient elastic, flexibility is chosen. The flexing of the spring member-must not stress it: beyond its limit of frame members andslidably fitting in bores 5l' in,

the other, 48, of such frame members to permit reciprocation oithe frame members toward and away from each other to cause operation of the. spring member 28 in generally'the same manner. as previously described; The relative reciprocation of the members 48 and 49 may be limited by any suitable means such as a link 52 secured. to one of the members 48, Land slotted to cooperate; with a screw stud 53 secured in the other of,

said members.

Though the device of Figs. 2-5 is shown as being symmetrical with reference to a median plane 26, such symmetry is not a necessity. For example, two frame members 54 and 55 (Fig. 7) may be hinged together at one side, as at 56, to permit the frame members to be moved toward and from each other to operate the spring memberzfl' in generally the same manner as previously described. The relative rocking movements of the frame members 54 and 55 may be limited by engagement of one against a projecting portion 57 of the other. Also, a. guide pin 58 secured. in the one frame member may slide in a bore 59 in the other.

Various other suitable forms of construction will readily be apparent.

The mechanical bi-stable device of the present invention may be used for many purposes and in various ways. 'For example, the device may, as shown in Fig. 9, have one or a plurality of bores formed in the frame member 2| with. a

' plunger 6!, 62, 63, '64, t5 and 66 slidable in each of such bores, each plunger being long enough to project into the opening 2! and outwardly from the outer side of the frame member 2']. The

' plungers may be utilized to operate desired devices such as electric. switches ii'l, E8, 69, l0, 7 I and '52. The plungers may each be urged inwardly either by a light compression spring 13 coiled about the plunger and confined between a shoulder M. on the plunger and a bushing I5 threaded into the bore in the frame 2|, or by external: yielding means such as, for example, a spring blade 16 of the switch operated by said plunger. It will readily be understood that. any of the switches may be so arranged for operation by the respective plunger that its contacts will be either opened or closed, asmay be desired, by the outward movement of the plunger by the spring member 26. In Fig. 9, switches 61, 69, 10 and 12 areself-opening but closed by outward movement of the associated plungers by the spring member 20, and switches 58 and H are self-closing but opened by outward movement of the associated plungers.

It will be apparent that as different portions of the spring member 253- mcve in diiierent directions and at different times'in the operation of the device, the plungers iiwill also move in different directions and at different times so that, consequently, the'switches 67-7? will be opened and closed at different times in a sequence which will be determined by the normal positions of the inner ends of the plungers relative to diiferent portions of the spring member. In the arrangement shown in Fig. 9 and starting with the spring member 20 in the position shown, the switches 61, 68, 10 and 12 will be open and the switches 69 and H closed. As the member 22 is depressed, the switch 68 will close, then the switch 10 will be closed, then the switch 69 will open and the switch 1| will be opened. As the member 22 returns to normal, the switch '12 will be closed and the switch 10 will open. Upon another reciprocation of the member 22, the switch 1| will close, then the switch 61 will be closed, then the switch 12 will open, then switch 08 will be opened, then the switch 69 will be closed and finally the switch 61 will again open. If desired, the plungers 83 and 66 may be so dimensioned and arranged, or the extent of inward movement of the member 22 may be sufficient, or the action of the spring member may be varied to cause operations of the switches 09 and/or 12 to be delayed until after the inward movement of the member 22 has been completed and the outward return movement thereof has started. The great number of variations which are possible will readily be apparent. It will be apparent also that any or each of the plungers (SI-6S may operate or control more than one pair of contacts.

It has further been found that the operation of the spring member from either of its stable forms and positions to the other of such forms and positions by each reciprocation of the mem-- ber 22 may readily be inhibited or prevented without interfering with the reciprocation of the latter. For example a further plunger 1'! (Fig. 8) may be slidably mounted in a bore in the frame 2I so that, when desired, it may be projected into the opening 21 in the mid-range between the point or 35' and the groove 24. When moved inwardly to project into the opening the plunger 11 will prevent the spring member til from having the form and position shown in Fig. 5. If the spring member 20 has the form and po-- sition shown in Fig. 5 just before inward movement of the plunger 11, the latter will shift the spring member to the form and position of the spring member 20 of Fig. 8. If, while the plunger 11 and spring member 20 have the positions shown in Fig. 8, the member 22 is moved inwardly, the spring member 20 will be moved to the form and position shown in Fig. 4 and, upon return of the member 22 to normal position, the spring member 20 will again return to the form and position of the spring member 20 of F'g. 8 instead of moving over to its other stable form and position. A second inhibitor 18 may also be provided on the other side of the spring 20. Such inhibiting means is useful for incur ing that the spring member 29 will be in a predetermined one of its stable positions following a. reciprocation of the member 22 regardless of which of its stable positions the spring nember previously occupied. If the spring member is not in the position of the spring member 26 of Fig. 8 when the member 22 is reciprocated while the inhibitor 11 is in its active inward position, the latter will not prevent the spring member 28 from being operated to that position but if the spring member 20 is in that position, the inhibitor will prevent the spring member from being operated to the other of its stable positions. Thus, with the inhibitor 11 or 18 in its active position, a reciprocation of the member 22 will insure that the spring member will be in the desired position.

The device may also be provided with two spring members 20 and 20 as shown in Fig. 8 arranged side by side and both secured to the same operating member 22. Normally, if both spring members start with corresponding forms and positions, they will be operated simultaneously upon each reciprocation of the operating member 22 and will remain in step. If, after any number of operations, the inhibitors 11 and 18 are moved to their inward effective positions, further reciprocations of the operating member 22 will continue to operate the spring member 20' from each stable position to the other alternately but will not so operate the spring member 20 while the inhibitors 11 and 18 remain in effective position. Thus, the device of Fig. 8 constitutes a means by which information accumulated up to a chosen time may be retained without alteration while further information continues to be accumulated.

The device may be operated by any desired means and in any desired manner as dictated by the use to which it is put. Operation of the member 22 may be effected by mechanical or electromagnetic means, such as a solenoid as shown in Fig. 9. The winding spool or bobbin 88 may be secured to the frame 2i or both may be secured to any suitable common support (not shown) and the movable magnetic core member BI may be secured in any suitable manner to the operating member 22 so that upon each energization of the winding of the solenoid, the member 22 will be depressed to its lower limit.

A new and advantageous binary counter employing electromagnetically operated mechanical bi-stable devices in accordance with the present invention is shown in Fig. 10. The counter comprises a series of the new mechanical bi-stable devices IDI, I02, I03, I04 and I05, there being one such device for each of the stages or orders 2, 2 2 2 and 2 of the counter. The spring members thereof are numbered I06, I01, I08, I09 and I I0 respectively. The movable spring-operating member 22 of each is secured to the armature or movable core member of an operating solenoid III, H2, H3, H4 or II5, respectively. Each of the devices IOI to I05 has one switch operating plunger H6, H1, H0, H9 or I20, respec-- tively, and each of those plungers, when its associated spring member I06, I01, I08, I09 or IIO moves from its left-hand stable position of Fig. 10 to its right-hand stable position, closes a pair of self-opening transfer or carry contacts I2I, I22, I23, I24 or I25, respectively, and also closes a pair of self-opening contacts I26, I21, I28, I29 or I30, respectively, controlling a respective one of a plurality of indicator or signal devices I3I, I32, I33, I34 or I35. When the associated spring member IOE-I I0 is being operated from either of its stable positions to the other, the opening or closing of the associated contact pair I 2 I-I25 does not occur until the operating member 22 for that spring member has been fully depressed and at least partially restored.

The pairs of contacts I2II25 and the windings of the solenoids IIII I5 are connected in circuit as shown in Fig. 10 with a desired source, such as the battery I36 and counting switch I31, of electric current impulses to be counted. The same battery I36, or a portion of it, may also energize the indicator or signal devices I3I-I35 through connections controlled by the pairs of contacts I26-I30 as shown in Fig. 10.

One terminal of the battery I36 is connected '9 to a grounded co ducto 5$ and ,thcothe m i conn te o ecqntac 9 s witch 4 1.- one is aint the ind-ing t sac... solenoid I,II.-i I5 is nected to the conductor 138 and the att c t r imal s connected to the co respo i one rot-a serie o se t cns of a cou tin ne conductor compr sin a s rie of sections MI, 142,443, 1.4.4 -;and- !45 corresponding i n be to he clim e -oi q sier it eo i er. Each countin iinesection =-t n c ed to one conta t o the conta t pai s 21.. 1 3, 1. 4 or 11-125 of the corres ondinsq e of the un e-othercontactiof ach.Qf aid pa r e cept he 4 a is 91 ct d t a respe. loneoial eriesi zmor b co acts i ifiof: t ineorizer izin rela con act of. the u in w ch I31 is connec d to anoth r no ah e onta t 45 of the z roiz n rela 3.3. Ee hof th va l ntacts M6 normally closed to a contact ,I 41 connected to the n xt :h hest orde section I42, 3, 1.4-4 ;or-.-I:!I15 of the-countin zline conductor. Thecontact 1-46 is norma ly closed a a nst a contact 1:411 connected to the lowes order section MI of the counting line conductor. The remaining ,con-tactof the contact pair I25 is connected to a zeroizing conductor I148 :having .a series or" contacts 149 connected thereto, the latter contacts -being.so arranged that, when the zeroizing relay l391isenergizedand the movable contacts vI 46 :and I46 thavebroken :from the .contacts I41 and IAFI,zthezmovablecontacts 1:46 and I46 willclose against respeotivezones1of thecontactsflfi.

The winding of :the-neroizing relay I 39 connected at one end 'to :ground .andat the .other end to one contactof a .zeroizing switch .I5.I., the other contactcfwhioh islconnectedzto a :tap on the battery I36. I

The contactpair 1.l;26,'| 2:1, I28, 4:29 0r|36 for each order and the signallorindicator device 131 I32, I33, I34 or :I 35for=the same order are connectedin series betweenthe conductor .I-38- anda conductor I52 connected .to a tap on the battery l3ii.

In the normal starting condition of the counter, as shown inFig. '1'0, all of the springs 106+ 0 are in their left-hand stable-positions, allthe contact palrs l 2'I 71:25am open so that each section |.H-|i4'5 0f th8 counting line conductor is isolated from theo-adjacent sections, all the l/ contact pairs 'I 26-I:3fl are open=so=that all-the-indL cator or signal devices I 3l'l35 are-off, the zeroizing switch I5[ is open so that-all the contacts M6 and i 56 are disengaged-irom the contacts 149 and closed with respectiveones-ot-the contacts I i? andMI'. The countingswitch I3 1 is also open.

When the countingswitch I31 isclosed to initiate the i first counting: pulse, the battery I36 is connected to the first order section "MI of the conning line and the first order solenoid III is energized and moves its armature downward and thus causes its spring [66 1 to be operated froni the position of the springjzfl of Fig., 2. to. the, full line position of1the spring,26 of .Fig. .4. The plunger I, I5 is. notjthereby operated. When the counting switch I3'Ijisagain opened, the solenoid III is de.-energized,.its armature restoresupe Wardly and the spring 1-! 06'; moves to the; pqfiitioil of the spring 20 of Fig. 5, thereby operating-.:.thfe plunger I I 6 tocloseicontact pair I2I to connect the second order section I42 of the counting line to the firstorder-sectiom I4I. "-Themlunger II6 veg 10 a so closes. t e o tact a r I26 to ene ze instia r t9 indi at 7? 1991 I 2- W1 -.ih -.e iii ins sw t i? a ain the connected-together first and second sections III-I and I42 of the counting line conductor are connected to the battery so that both of the sole-.- noids III and I it are energized. The plunger i I6 does not permit the contact pairs I2I and I26 to reopen nn-til the armature of solenoid III has been fully depressed and partially restored and plunger II! is not operated to close contact pairs I22 and IZ'I until the armature of solenoid I 12 has been fully depressed and partially restored, i. :e. until after counting switch I3! is reopened, at which time spring I66 returns to its left-hand stable position while the spring It! moves to its right-hand stable position. At that time the only indicator device energized will be the indicator I32, indicating a count of 2 Counting line sections I42 and I43 will be connected together by contact pair I22 but isolated from counting line section MI by the opened contact-pair IZ-I A third closing and opening of the counting switch I31 will cause the solenoid I I I, spring I06 and contact pairs I 2I and I 26 0f the first order to be operated exactly as they were by the first closing and opening of that switch. After such third operation of the counting switch, the two indicators [3| and 1,32 will both be energized to indicate a count of ,2+ 2 and the three lowest order sections I4I, I42 and I93 of the counting line will be connected together. A fourth operation of the counting switch -I3'I will, therefore, cause the threelowest order solenoids ,III, II2 and M3 to be operated. The solenoids III and H2 then operate the springs I66 and It! again to their left-hand stable positions and the solenoid II3 operates the spring its to its righthand stable position. The counting line sections I43 and I44 will then be connected together through'the closed contact pair I2'3'but the other counting line sections will be separated at the open contact pairs I21, I 2-2, -I24 and I25. Only the indicator I33 will be energized, indicating a count of 2 From theforegoing the operation of thecounte er for successive further operationsof the counting switch I37 will easily be apparent. It Will be seen thatthe eighth operation of the counting switch will cause operation of the four solenoids II IeIQM and oftheir springs I06-I0$and that the sixteenth operation vof the counting switch will cause operation of the fivesolenoids i-II-I I5 and springs I'D6-.I I0. The lowest order solenoid III and its spring Hi6 are operatedupon each operation or" the countingswitch I37, the solenoid -I I2 and its spring .167 are operated simultaneously with each secondoperation.ofthe solenoid I,I;I,the solenoid H3 and its springJOB are operated simultaneously with each second operation of the solenoid I. I2, .and so on. Each operation of any one of the spring members I06-I I0 reverses it fromlone to the otherof its stable positions and also reverses the on or off condition of its associated indicator -I 3I- I35.

To reset or zeroize the counter atany timeit i necessary t o ev the. zeroizi rs switch. i5! a d h cou in w tch I 1 t e re pe h att tacts H1 and I41 and closes the contacts I46 and I46 with their companion contacts 149, If any spring member IDS-I Ill is in its right-hand stable position as the switches I31 and Ii are closed, the associated one of the contact pairs l2I-I24 will be in closed condition and the closing of the switch I37 will complete an energizing circuit for the respective one of the solenoids Ill-l [5 through the contacts Hi9 and the zeroizing line I48 to operate that spring to return it to its left-hand stable position. Then, the springs IDS-H5 will all be in their lefthand stable positions, all contact pairs l26-I3ll will be open so that all indicators I 31-135 will be oil, and all. contact pairs l2|-l25 will be open so that when the switches I31 and [5| are reopened in that order, the counter is again in the condition shown in Fig. 10 and ready for accumulation of a new count.

I claim:

1. A bi-stable device comprising an elongated elastically flexible spring member, means to support said spring member pivotally at one end to accommodate rocking of the adjacent portion of said spring member about said end, means to support the other end of said spring non-pivotally, means mounting one of said supporting means for movement readily toward and from the other supporting means to operatively reciprocate the thereby supported end of the spring member toward and from the other end thereof, limit means cooperating with the movable supporting means and positioned to hold maximum separation of the ends of the spring member to a distance less than the length of the spring member and thereby cause said spring to be bowed away from a line through the ends of the spring member, confining means located on opposite sides of said line and positioned to block, during each movement of said movable supporting means toward the other supporting means, increased bowing and movement away from said line of the portion of said spring member extending from said pivotally supported end to a point in its length a short distance beyond the point farthest displaced from said line and thereby compel a portion of said spring member nearer to the non-pivotally supported end thereof to be increasingly bowed in the opposite direction and shifted progressively across said line by such movement of said movable supporting means until said spring member reaches an unstable substantially sinuous form and position from which it can spontaneously shift further in the same sense and, upon reverse movement of said movable supporting means to the extent permitted by said limit means, spontaneously transform to the form and position reversed, with respect to said line, from the form and position it had prior to such reciprocation of the movable supporting means.

2. A device according to claim 1, having a stationary support, an output member movably mounted in said support for movement by a portion of said spring member as such portion moves during at least a portion of the operation of said spring member from one normal stable position to the other normal stable position.

3. A device according to claim 2, having at least one other output member movably mounted in said support for movement by another portion of said spring member as said latter portion moves during a different portion of said operation or said spring member.

4. A device according to claim 2, having at least one other output member movably mounted in said support for movement by a portion of said spring member as such portion moves during at least a portion of the operation of said spring member from said other normal stable position to said one normal stable position.

5. A device according to claim 1, having an inhibitor member normally outside of the range of movement of said spring member and mounted for movement to engage said spring member when the latter is in one of its two stable normal positions and shift the portion of said spring member located between said confining means toward said line to a position from which, upon relative movement of said movable supporting means toward the other supporting means while said inhibitor member is in such moved position, the last-mentioned portion of said spring member will bow toward said line and the remainder of said spring member will not shift toward or across said line and said spring member will assume a form and position from which it will, upon return of said movable supporting means to its normal position determined by said limit means, return to the form and position it had prior to such relative reciprocation of said supporting members.

6. A device according to claim 1, having an electromagnetic actuating means including portions movable relatively to each other upon energization of said electromagnetic means, said relatively movable portions being operatively connected with said two supporting means respectively to reciprocate said movable supporting means by successive energizations and de-energizations of said electromagnetic means.

7. A binary counting device for use as a stage in plural stage counter and comprising a bistable device as defined in claim 1, an electromagnetic operating device including an electrical operating winding and relatively movable ele ments connected with said two supporting means, respectively, to reciprocate the movable supporting means toward and from the other supporting means upon energization and de-energization of said winding, first and second input terminals for said stage connected respectively with the opposite ends of said winding and said first terminal being adapted for connection to the first terminals of like counting devices of other stages of such counter, a third terminal adapted for connection to the second terminal of a like counting device of the next higher stage of such counter, and means associated with the second and third terminals of the counting device and operated by movement of said spring member into one of its stable normal positions to electrically connect said second terminal to said third terminal and, by movement of said spring member into the other of its stable normal positions, to disconnect said second and third terminals from each other.

8. A device according to claim 7, having a pair of conductors for connection to an electrically operable indicator means, and contact means associated with said pair of conductors and operable by said spring member to establish electrical connection between said conductors when said spring member is in one of its stable positions and to break said connection when said spring member is in the other of its stable posilOIlS.

EDGAR ALAN BROWN.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Pfeifer July 3, 1928 Prosser Jan. 7, 1936 Bryce July 2, 1940 Guenther May 8, 1945 Tiffany Feb. 26, 1946 Singleton Apr. 20, 1948 Blyholder June 8, 1948 14 Number Name Date 2,444,042 Hartley June 29, 1948 2,448,230 Miller Aug. 31, 1948 2,479,313 Clark Aug. 16, 1949 5 2,501,497 Clark Mar. 21, 1950 OTHER REFERENCES AIEE Technical Paper 49-148; Counting With Relays by G. R. Frost. Copy in Div. 23, 10 May 1949. 

